This invention relates to an oil supplying device for a two cycle engine and more particularly to an improved pumping arrangement for delivering lubricant to an engine.
It is well known that internal combustion engines require lubricating systems and four cycle engines normally employ a crankcase and lubricating system wherein the oil is pumped to the engine for lubrication and return to the crankcase. With a two cycle engine, on the other hand, the lubricant is normally supplied with the intake charge and frequently is mixed with the fuel so that it will be in contact with the parts of the engine to be lubricated and then is discharged through the exhaust of the engine. Recently it has been proposed to provide a separate lubricating system for engines wherein the lubricant is not mixed with the fuel but rather is delivered to the engine by some form of pump. However, since the lubricant is discharged to the atmosphere it is extremely important to insure that the amount of lubricant supplied under some running conditions is quite small. Conventional pumps cannot handle accurately such small amounts of lubricant flow.
It is, therefore, a principal object of this invention to provide an improved lubricant supply system for an internal combustion engine.
It is a further object of this invention to provide a lubricant supply system for an internal combustion engine in which very small amounts of lubricant can be delivered.
It is a further object of this invention to provide an improved lubricating system for a two cycle internal combustion engine.
In connection with the lubrication systems for two cycle engines, it is possible to drive the lubricant pump in a number of manners. Pumps that are driven mechanically from the engine output shaft or some other rotating component of the engine obviously complicate the engine construction. It is also possible to use an electrically driven pump for his purpose but such pumps require obviously a battery or power source. Thus, this also complicates the engine. Therefore, it has been the practice to employ a pulsating type pump that is of the diaphragm or piston type and which is operated by the crankcase pressure variations that exist with such engines. Such devices have the advantage of being quite simple and can be located in any of the a wide variety of locations relative to the engine. However, this type of pumping device has several disadvantages.
In the first instance, it is quite difficult to have this type of pump, which is generally a positive displacement pump, pump the small amounts of lubricant as aforenoted. Furthermore, the amount of lubricant pumped by this type of pump can vary with the level of the lubricant in the supply tank that feeds the pump and also with changes in viscosity as occur due to temperature variations. In addition, by its very nature and cyclic operation the quantity of lubricant pumped by the pump will fluctuate.
It is, therefore, a still further object of this invention to provide an improved and simplified positive displacement pump for delivering lubricant to an engine.
It is a still further object of this invention to provide an improved, simplified lubricant pump that will pump small quantities of lubricant and without having significant cyclic variations.